Conventionally, difficultly water-soluble photographic useful reagents (e.g., oil-soluble couplers, antioxidation products (e.g., alkylhydroquinones, alkylphenols, chromans, coumarones) for use in preventing fading, color fogging or color mixing, hardening agents, oil-soluble filter dyes, oil-soluble ultraviolet light absorbers, oil-soluble fluorescent brighteners, DIR compounds (e.g., DIR hydroquinones, non-color forming couplers), developing agents, color developing agents, DDR redox compounds, DDR couplers and the like are dissolved in appropriate oil forming agents, that is, high-boiling solvents, the resulting solutions are dispersed in a hydrophilic organic colloid, particularly a gelatin solution, in the presence of a surfactant, and the resulting dispersions are contained in hydrophilic organic colloid layers (e.g., light-sensitive emulsion layers, filter layers, back layers, antihalation layers, interlayers, protective layers). Phthalic ester compounds and phosphoric ester compounds are generally used as high-boiling organic solvents.
Phthalic ester compounds and the phosphoric ester compounds are conventionally widely used as high-boiling organic solvents because they have excellent coupler dispersibility and affinity with colloids such as gelatin, have an excellent effect on the stability and hue of developed dye images and are chemically stable in the photographic materials and are inexpensive.
However, these conventional high-boiling organic solvents (e.g., the phthalic ester compounds and the phosphoric ester compounds) are still insufficient in preventing dye images from being faded by light, heat and humidity and in preventing stain from forming when they are used in current photographic materials for which high performance is required.
The high-boiling organic solvents used in current photographic materials must meet various requirements. For example, they must generally meet such requirements that they are inexpensive, can be easily prepared, have excellent solubility and dispersion stability as photographic reagents, do not have adversely affect developability and photographic characteristics, are excellent in safety, do not pollute the environment, have excellent effects in preventing dye images from being faded and have excellent chemical stability.
Dyes formed from couplers, particularly pyrazoloazole magenta dyes and pyrroloazole cyan dyes tend to be associated in the layers. The maximum absorption wavelengths of the associates thereof are different from those of the dye monomers. When the absorption of the associates is too large, this absorption is unfavorable for color reproducibility.
If the maximum absorption wavelengths of the dyes can be controlled by making the wavelengths longer or shorter by using additives in the same layers as those in which the dyes are present without changing the structures of the dyes themselves, silver halide color photographic materials having better color reproducibility can be prepared with low manufacturing costs.
It has been found that certain compounds of the high-boiling organic solvents capable of being used as dispersion mediums for dye-forming nondiffusion couplers have an effect of making the maximum absorption wavelength of each of yellow, magenta and cyan dyes longer or shorter and an effect of inhibiting or accelerating the association of the dyes to thereby change the absorption wave form. These compounds are drawing attention.
Examples of these compounds include phosphine oxides, phosphinic esters and phosphonic esters described in JP-A-63-301941 (the term "JP-A" as used herein means an "unexamined published Japanese patent application") and JP-A-2-4239, urea compounds described in European Patent 0 309 158 A1, sulfonamide compounds described in European Patent 0 309 159 A1 or JP-A-4-346338 and amide compounds described in European Patent 0 309 160 A1. However, it is often difficult for these compounds to improve the hue of the dyes and at the same time, as dispersion mediums, to improve the solubility and dispersion stability of additives used. Further, the developability of the dye-forming nondiffusion couplers is often reduced. Furthermore, when these compounds and the dye-forming nondiffusion couplers are used in the same layer, the dyes formed from the couplers are often faded by heat, humidity and light.